Final answer:
Metamorphic rocks are most abundantly found in mountain belts, often exposed due to erosion of overlying rocks. High-grade metamorphic rocks are typically central to regions of ancient tectonic collisions. Regions like the Chugach Metamorphic Complex and the Northern Highlands of Scotland are key examples.
Step-by-step explanation:
Metamorphic rocks are most abundantly exposed in outcrops in mountain belts or ancient mountain belts, particularly where there has been significant geological activity, such as tectonic plate collisions. The process of metamorphism involves the alteration of pre-existing rocks through heat and/or pressure, which predominantly occurs in these geologically active regions. Erosion is a key process in exposing the higher grade metamorphic rocks to the surface, with uplifting mountain belts providing increased surface area for weathering and erosion. The Barrovian sequence models this exposure, as it shows a gradient with the highest grade metamorphic rocks near the center of a tectonic collision and gradually decreasing in grade outward.
To observe high-grade metamorphic rocks, such as gneiss which is formed from high degree metamorphism, one should look towards the centers of old mountain ranges or regions where continental collisions have taken place. These deep geological structures can sometimes be exposed on the Earth's surface through geological forces and are often represented by folded or tilted strata, as seen in locations like the Chugach Metamorphic Complex in southern Alaska or the Northern Highlands of Scotland.